National Libraries Day falls this Saturday, but this year the celebrations will be tinged with a deep sense of alarm. The future of libraries is more uncertain than it has been in decades. Almost 600 libraries are currently under threat, as councils are forced to slash spending. Opening hours and book budgets are being reduced. Savings have to be made, but this attack on libraries underestimates their value, and ignores the less destructive alternatives.

Libraries can be real hubs of their communities, responsive to them, helping them to flourish. Reading has to be at the heart of the mix (I don't buy for a second the idea that books are obsolete). This is all the more important at a time when four million children in the UK don't own a book, and when as many as one in six adults have trouble reading; illiteracy is thought to cost our economy up to £81bn a year. The benefit of libraries to communities is harder to measure, but I've seen it with my own eyes, in libraries large and small, from Barnsley to Bermondsey.

Does this government see it? Libraries minister Ed Vaizey's stock line has been: "I don't run library services. Local authorities do." He has a point: libraries are run by democratically elected local governments, and they take the lead. But that's no excuse for doing nothing. It may not be Vaizey's job to micro-manage every library in the country – but it is his job to be their champion. And that is what he is failing to do.

How can he claim otherwise, when he seems happy to leave the courts to do his job for him? Vaizey says he has not intervened because a few authorities have managed to reverse proposals for widespread cuts after a judicial finding against them; therefore, he airily asserts, campaigning works. But what about the places that are not lucky enough to have a cadre of dedicated people who can scrape together the money to mount a legal challenge? What if their case fails, or runs out of funds?

The minister should not leave it to the courts to decide when something has gone wrong. He and his department need to take a view. By law it is he – not hard-pressed, ad-hoc campaigns that tend to be in the more affluent parts of the country – who has ultimate responsibility for libraries.

No minister can seek to prevent all cuts, but they can be engaged and active. They can ensure that closures don't happen without due process and consultation, and offer advice on savings, such as streamlining back-office operations or co-locating a library with other services.

Above all, a minister can promote as well as defend the service. Vaizey often says the right thing, but you wonder whether he really gets it. There is plenty of talk about the Big Society, which seems to mean pressuring reluctant community groups into running libraries for free. What is missing is a coherent, long-term vision, a true sense of excitement about the potential of libraries – and, critically, a credible plan for realising it.

As shadow arts minister, I am in the process of developing such a plan. But Vaizey could start with a comprehensive review of how libraries can be plugged in to the wider work of government, through regular engagement between ministers and senior civil servants (currently this discussion happens at a much lower level). He could co-ordinate an overdue marketing effort to boost awareness of libraries among the public. He could fully engage in the fight to prepare libraries for the digital future, instead of scrapping Labour's plans to extend the Public Lending Right to e-books. These steps would require a modest amount of funding, but have a major impact. At present, the Arts Council is valiantly trying to do some of these things, but it is far too little – and for the 75 libraries that have closed in the last 10 months, it is too late.

The current wave of closures should be a call to arms – not because libraries should be exempt from bearing their share of budget cuts (as long as it is a fair share), but because what is happening ignores their enormous value. If this government really believes in the promise of libraries, they must act now.

• This article was amended on 2 February 2012. The original referred to the Public Borrowing Right. This has been corrected. The word 'ensure' was reinstated in the following sentence, after being edited out in the original version: 'They can ensure that closures don't happen without due process and consultation, and offer advice on savings, such as streamlining back-office operations or co-locating a library with other services.'